Ketamine hydrochloride, diluted four-fold in 0.9% solution of NaCl, was injected into the epidural spaces of 10 animals at 2 mg/kg body weight and of another 10 animals at 3 mg/kg. For both dosages, at least five minutes were required for the onset of adequate surgical analgesia for perineal surgery. At 2 mg/kg body weight epidural ketamine induced analgesia for 45 to 60 minutes (mean: 55 minutes), while 3 mg/kg provided analgesia for 55 to 70 minutes (mean: 60 minutes). Significant alterations were not detected in the mean respiratory rates, heart rates or body temperatures at any time up to 75 minutes after injection. Analgesia provided by epidural ketamine was satisfactory for superficial operations in the perineal region; however, there was inadequate muscle relaxation for some operations such as post-scrotal urethrotomy and correction of vaginal prolapse; in those situations it would be necessary to administer a muscle relaxant in conjunction with the epidural ketamine.